Calibration of automatic circuit breakers



I July 28, 1953 T.v M. COLE 2,647,187

CALIBRATION OF AUTOMATIC CIRCUIT BREAKERS Filed March 2. 1951 5' INVENTOR.

THOMAS M. COLE Patented July 28, 1953 CALIBRATION F AUTOMATIC CIRCUIT BREAKERS Thomas M. Cole, New York, N. assignor to Federal Electric Products Company, Newark, N. J a corporation of Delaware Application March 2, 1951, Serial No. 213,591

13 Claims. (01. ZOO- 116i This inventionrelates to an. improved method of calibrating automatic circuit breakers and to circuit breakers which are adapted for the prac tice of. said method.

This: application is a continuation-in-part of my copending. application for circuit breakers Ser. No. 127,433 filed November 15, 1949.

The primary object of the present invention is to provide a simplified and yet micromatically accurate method for calibrating an automatic circuit breaker.

Another object is provision in an automatic circuit breaker of simplified means for adjusting the relative disposition of the actuating means and the bi-metallic element for latch thereof for calibration purposes.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings Fig. 1 is a perspective view of an automatic circuit breaker illustrating the calibrated condition thereof pursuant to the presently preferred mode of practicing the present invention, the cover or one side of the casing being removed and the breaker being closed;

Fig. 2 is a fragmentary view of a sub-assembly of the circuit breaker mechanism. in uncalibrated condition;

Fig. 3 is a view similar to Fig. 2 showing the sub-assembly thereof in calibrated condition, pursuant to one method of practicing the invention;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 3;

Fig. 5 is a composite view similar to Figs. 2 and 3, illustrating the presently preferred embodiment of the invention before the tapered tool i removed; and

Fig. 6 is a sectional view taken on the line 6--6 of Fig. 5.

In general, the circuit breaker illustrated herein and in my above mentioned prior application comprises a movable contact member which carries the movable contact for engagement with and disengagement from the stationary contact of the circuit breaker. Said movable contact member is provided with an actuator which is releasably latched to said movable contact member by means of a current responsive or other overloaddevice which is carried by the movable contact member and releasably engages said actuator under normal load conditions so as to I enable the movable. contact member to be held in circuit closed position, or to be manually moved to and from said position, and which, upon re lease of said actuator, results in the movement of said movable contact member automatically to its open circuit position.

Briefly described, the provision for calibratin the circuit breaker, pursuant to the present invention, comprises means to facilitate displacement of a part of the movable contact member of the circuit breaker in. relation to another part thereof in such manner as to move the actuator in relation to the current responsive or overload device so as to adjust the releasably engaged portions of the actuator and the current responsivedevice. In accordance with the presently preferred mode of practicing the present invention, an opening is provided at the edge of said part of the movable contact member and a tapering pin or other tool is pressed into said opening for accomplishing the displacement of said part of the movable contact member. Although it is presently preferred that the tool be removed from said opening, following the calibration operation, it is Within the scope of the present invention to allow the tapering pin, used as the calibratin tool, to remain permanently in said opening of the movable contact member.

Referring now to the drawings in detail, there is shown in Fig. 1 an automatic circuit breaker 10 provided with the body part l2 of a two part insulated. casing or housing, as in my above mentioned application, the cover thereof being removed for purposes of illustration of the present invention. The circuit breaker mechanism I I provided in said body part, as here shown, comprises the pivotally mounted movable contact arm l4 provided with the movable contact 16 at one end thereof for engagement withv and disengagement from a companion stationary contact I8 provided on a solderless terminal connector 20. At its other end, the movable arm M is, provided with a pivotally mounted actuator 22 which is in operative engagement with the handle or manual operating member 24 by means of a. resilient link 26. The movable contact arm it is alsov provided with a bi-metallic element orlatch 28, the free end of; which is in latched engagement with the actuator 22' in the circuit-makin or closed condition of the mechanism. The

latch is connected to a stab, element 3.0, which constitutes the other terminal of the circuit breaker, by; means of a flexible conductor 32. As: hereshowm the mechanism is also provided with:

electro-magnetic means for effecting the disengagement thereof, said means comprising the magnetic member 34 carried by the latch 28, and the rigid armature 36 which is secured at one end thereof to the latch and to the movable contact arm. A spring 38 is interposed between the handle 24 and the movable arm [4, as illustrated.

The operation of the circuit breaker is described in detail in my above mentioned copending application. However, it will be understood that the bi-netallic element 28 operates to latch the manually operable actuator 22 to the movable contact member I4 and to unlatch said actuator from the movable contact member, the unlatching taking place upon deflection of the bi-metallic element 28 causing the disengagement of the free end 48 thereof from the bottom part 42 of the actuator 22 upon the occurrence of an overload, or under other abnormal predetermined current conditions in the circuit controlled by the circuit breaker. When the bi-metallic element 28 is deflected from engagement with the actuator 22, spring 38 is effective to move the contact member E4 to its open position, as illustrated in my copending application, wherein the contact [6 is disengaged from the companion stationary contact l8.

Pursuant to the present invention, and in order to provide for the fine or micromatic adjustments of the actuator for calibration purposes, the movable contact member i4 is provided with a generally circular, peripherally interrupted aperture 44. Said aperture is formed in the lower marginal edge of the narrower portion 46 thereof, on the free end of which the actuator 22 is pivotally mounted. It will be noted that the body portion 48 of the movable contact member [4 forms the wider and generally larger portion thereof and extends to the left (viewing Fig. l) of the pivot pin 58 on which the movable contact arm is pivotally mounted.

The mechanism l I is calibrated preferably prior to the insertion thereof in the housing portion l2. For calibration purposes, pursuant to my invention, it is necessary to provide only a sub-assembly l3 of the circuit breaker l0. Said sub-assembly includes the movable contact arm l4, the actuator 22 mounted at one end thereof, and the bi-metallic latch 28 which is secured at the bottom edge of the body portion 48 of the contact arm. In the uncalibrated condition of said subassembly l3, as illustrated in Fig. 2, the bottom or latching part 42 of the actuator may overlap substantially the full thickness of marginal edge 52 at the free end 48 of the bi-metallic latch. Then, with the movable arm l4 retained against movement, preferably in a suitable clamp or fixture (not shown), a tapered element or pin 54 is inserted into the aperture 44 and urged therein transversely of the movable member in any suitable manner. This will result in the displacement of the movable member l4 in its own plane. More specifically, the narrower portion 46 will bend upwardly, in the plane of movable arm [4, relative to the wider body portion 48 thereof. This will carry actuator 22 upwardly relative to latch 28 to decrease the extent by which the end part 42 of the actuator 22 overlaps the marginal edge portion 52 of the latch 28, for example, as illustrated in Fig. 3. Said figure corresponds to the Figure in my copending application, the pin 54 corresponding to the pin H8 illustrated in said figure of said copending application. In this manner of practicing the invention, the pin remains in its adjusted position in the aperture, the opposing portions 56 and 58 at the nterrupted periphery thereof being moved away from each other by the displacement resultin from the insertion of said pin.

Pursuant to the presently preferred embodiment of my invention, illustrated in Figs. 5 and 6, the pin 54 is dispensed with and, in place thereof, I prefer to use a spindle or tool 68 provided with a tapered end 62. The sub-assembly l3, comprising the movable arm l4, the actuator 22 and the latch 28 is then retained as heretofore described. The spindle 88 is then inserted into the aperture 44 and urged therein by means of any suitable mechanism, until end portion 46 of the latch 28 has been displaced sufficiently upwardly in the plane of member [4 to provide the desired degree of overlap of the actuator end 42 on the latch edge 52 to obtain the desired calibration. This is clearly indicated in Fig. 5 wherein the uncalibrated sub-assembly is illustrated in broken line, said sub-assembly being in the same condition as illustrated in Fig. 2. The tapered end 62 of the spindle 6D is then pressed into the aperture until the portion 48 of the movable member l4 has been displaced in the plane thereof to the desired extent, as indicated in full line in Fig. 5, to illustrate the calibrated condition of the subassembly. The spindle 68 is then withdrawn from the sub-assembly which is now ready to be inserted into the housing part I2. Upon the proper placement of all the parts in the housing, the calibrated mechanism will be in the condition illustrated in Fig. 1. It-will be apparent that further calibration is unnecessary since the subassembly has been calibrated prior to incorporation in the housing.

It will be noted that in the described methods of practicing my invention, the bi-metallic latch 28 is not moved during calibration since it is secured to body portion 48 of the movable member [4, which portion is not displaced. It is the actuator 22 which is moved relative to the latch since the actuator is carried by portion 46 which is displaced during calibration.

While I have shown and described the preferred embodiment of my invention, it will be understood that various changes may be made in the present invention without departing from the underlying idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by letters patent, is:

1. In an automatic circuit breaker, a movable contact member, said movable contact member having an actuator movably mounted on a part thereof and having a current-responsive device releasably engageable with said actuator for releasably latching said actuator to said member for movement of said member by said actuator, means for use in calibrating the circuit breaker comprising provision in said part of said member of means to facilitate displacement of said part in said member and thereby move said actu ator in relation to said current-responsive device for adjusting the releasably engaged portions of said actuator and said current-responsive device.

2. In an automatic circuit breaker, a movable contact member, said movable contact member having an actuator movably mounted on a part thereof and having a current-responsive device releasably engageable with said actuator for releasably latching said actuator to said member for movement of said member by said actuator, means for use in calibrating the circuit breaker comprising provision in said part of said memher of means to facilitate displacement of said part in said member, said means comprising "an opening at an edge portion of the member to receive a tool for causing said displacement of said part of the member and thereby move said actuator in relation to said current-responsive device for adjusting the releasably engaged portions of said actuator and said current-responsive device. I

3. In an automatic circuit breaker, a movable contact member, an actuator movably mounted thereon, a thermallyrespons'ive oi-metallic element carried by said member and having a free end in releasable engagement with said actuator to latch and unlatch said member thereto, said actuator and said element being provided on spaced portions of said member and means provided in said '"ember to facilitate the relative displacement of said portionsffor moving said actuator relative to said free end whereby to calibrate said circuit "breaker, said means com prising a marginal edge portion of said member in which there is defined a peripheral interruption.

4:. In an automatic circuit breaker which comprises a movable contact member having an actuator movably mounted thereon and a thermallyresponsive bit-metallic element carried by said member and having a free end in releasable engagement with said actuator to latch and unlatch said member thereto, means for use in calibrating the circuit breaker comprising provision in said member to facilitate the displacement thereof for moving said actuator relative to said free end whereby to calibrate said circuit breaker, said means comprising a marginal edge portion of said member in which there is defined a peripheral. interruption, said edge portion being between the respective points of said member on which said actuator is mounted and said ele ment is carried,

5. In an automatic circuit breaker, a movable contact member, an actuator movably mounted adjacent one end thereof, a thermally-responsive oi-metallic element carried adjacent the other end of said member and extending therefrom for releasable engagement with said actuator to latch and unlatch said member thereto, and means provided in said member to facilitate the displacement of said one end thereof relative to said other end thereof for moving said actuator relative to said element whereby to calibrate said circuit breaker, said means comprising a marginal edge portion of said member disposed between said ends thereof and provided with a pcripheral interruption.

6. In an automatic circuit breaker, a movable contact member, an actuator movably mounted adjacent one end thereof, a thermally-responsive bi-rnetallic element carried adjacent the other end or" said member and extending therefrom for releasable engagement with said actuator to latch and unlatch said member thereto, and means for calibrating said circuit breaker comprising a marginal edge portion of said member disposed between said ends thereof and provided with a peripheral interruption, and means in said peripheral interruption for moving said one end relative to said other end in the plane of said member for moving said actuator relative to said element.

'7. A movable contact member for an automatic circuit breaker, said member having a marginal edge portion in which there is defined a peripherally interrupted aperture to facilitate the displacement of a portion of said member 6 in itszown plane for calibrating the circuit breaker, and a tapered member in said aperture for effecting said displacement.

8. The method of cah-brating a circuit breaker provided "with a movable contact member having an actuator movably mounted on a part thereof and a current-responsive device releasably engageable with said actuator for releasably latching said actuato'rto said member for movement of said member by said actuator, said method comprising displacing said part of the movable :contact member relatively to another part thereof so as to move said actuator in relation to said current-responsive device for adjusting theireleasably engaged portions of said actuator and'rsaid current-responsive device.

'9. The method of calibrating a circuit breaker provided with a movable contact member having an actuator movably mounted on a part thereof and having a current-responsive device releasably engag'eable with said actuator for rel-easably latching said actuator to said member for movement of said member by said actuator, said method comprising providing an opening at an edge of said part of the movable contact member and pressing a tapered member into said opening transversely of the general plane of said part for displacing said part relative to another part of said movable contact member so as to move said actuator in relation to said currentresponsive device for adjusting the releasably engaged portions of said actuator and said ourrent-responsive device.

10. The method of calibrating a circuit breaker provided with a movable contact member having an actuator movably mounted on a part thereof and having a current-responsive device releasably engageable with said actuator for releasably latching said actuator to said member for movement of said member by said actuator, said method comprising providing an opening at an edge of said part of the movable contact member and pressing a tapered member into said opening transversely of the general plane of said part for displacing said part relative to another part of said movable contact member so as to move said actuator in relation to said current-responsive device for adjusting the releasably engaged portions of said actuator and said current-responsive device, and thereafter removing said member from said movable contact member.

11. The method of calibrating a circuit breaker provided with a movable contact member having an actuator movably mounted on a part thereof and having a current-responsive device releasably engageable with said actuator for releasably latching said actuator to said member for movement of said member by said actuator, said method comprising providing an opening at an edge of said part of the movable contact member and pressing a tapered member permanently into said opening transversely of the general plane of said part for displacing said part relative to another part of said movable contact member so as to move said actuator in relation to said current-responsive device for adjusting the releasably engaged portions of said actuator and said current-responsive device.

12. In an automatic circuit breaker having a movable contact member, actuating means mounted thereon, and a thermally-responsive bimetallic element carried thereby for releasable engagement with said actuating means to latch and unlatch said member thereto, said actuating means overlapping said element in the engaged condition thereof; the method of calibrating said circuit breaker comprising providing said movable member with a peripheral interruption intermediate said actuating means and said element and enlarging said interruption to displace a portion of movable member provided with said actuating means in the plane thereof for adjusting the extent of said overlap.

13. In an automatic circuit breaker having a planar movable contact member provided with a body portion and a narrowed extension, actuating means mounted on said extension, and a thermally-responsive bi-metallic element carried on said body portion and extending therefrom for releasable engagement with said actuating means to latch and unlatch said member thereto, said actuating means overlapping said element in the engaged condition thereof; the method of calibrating said circuit breaker comprising providing a peripherally interrupted aperture in a marginal edge portion of said member between said narrowed extension and said body portion, in-

serting a tapered element into said aperture and pressing said tapered element into said aperture for moving said narrowed extension in the plane of said movable member and relative to the body portion thereof for adjusting the extent of said overlap.

THOMAS M. COLE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,952,040 Frank et a1. Mar. 20, 1934 2,134,565 Leonard Oct. 25, 1938 2,174,669 Sachs Oct. 3, 1939 2,209,319 Christensen July 30, 1940 2,209,352 Sachs July 30, 1940 2,209,353 Sachs July 30, 1940 2,302,551 Jackson Nov. 17, 1942 2,315,633 May Apr. 6, 1943 2,459,427 Humpage Jan. 18, 1949 

